JPH07103081B2 - Method for producing α-hydroxyisobutyramide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing α-hydroxyisobutyramide. More specifically, it relates to a method for producing α-hydroxyisobutyramide (hereinafter abbreviated as HAM) by continuously reacting acetone cyanohydrin (hereinafter abbreviated as ACH) and water in a liquid phase. Is.

[Conventional technology]

It is generally known that an amide compound can be formed by reacting a corresponding nitrile compound with water, and various catalysts effective for this reaction are known.

The manganese oxide described in US Pat. No. 3,366,639 is one of them.

Copper-containing catalyst often used for hydration of nitrile compounds,
On the contrary, manganese oxides, as disclosed in West German Patent No. 2,131,813, also give poor results for hydration of α-hydroxynitrile compounds such as ACH. It has the characteristic of giving considerable results.

Further, in JP-A-52-222, the presence of lignite as a catalyst,
It is described that when producing HAM by hydrating ACH in the temperature range of 60 to 90 ° C., the yield of HAM can be increased by adding acetone to the reaction mixture.

Furthermore, when a manganese oxide obtained from a heptavalent manganate and hydrohalic acid is used, variations in catalyst activity are eliminated, and the performance of the catalyst is also improved, as disclosed in JP-A-63-57,535. It is disclosed.

[Problems to be Solved by the Invention]

However, West German Patent No. 2,131,813 in the prior art
Hydration of ACH under the reaction conditions given in the examples of the publication has the disadvantage of low HAM productivity of the catalyst.

Further, the specific implementation method using the catalysts shown in JP-A-52-222 and JP-A-63-57,535, in which acetone is added to the reaction system, is a batch reaction, which is an industrial method. The production method has a drawback that the efficiency is very poor.

Therefore, as a result of examining the industrial continuous production method of HAM by hydration of ACH, the present inventors have found that at the temperature used for the batch reaction described in the specific examples of the prior art, the catalyst The activity was found to decrease rapidly with time.

Therefore, in industrially continuously producing HAM by hydration of ACH, frequent catalyst exchanges due to decrease in daily activity of manganese oxide catalyst and increase in catalyst cost are major problems. Maintaining the long-term activity of oxide catalysts is the greatest challenge.

Further, conventionally, in the method for producing HAM by hydration of ACH, various reaction conditions have been reported, as seen in the above-mentioned patents and documents, but manganese oxidation in view of an industrial continuous production method has been reported. Nothing has been reported about the extension of the life of the physical catalyst.

[Means for Solving the Problems]

The present inventors have conducted an earnest study to eliminate the above-mentioned problems of the manganese oxide catalyst in order to industrially continuously produce HAM economically by hydration of ACH. It was found that the activity of the manganese oxide catalyst can be maintained for a very long period of time by hydrating ACH in the temperature range of 30 to 55 ° C. in the coexistence of, and the present invention was completed.

That is, the present invention, when producing HAM by continuously reacting ACH and water in a liquid phase, using a manganese dioxide catalyst prepared from manganese sulfate and potassium permanganate under sulfuric acid acidity, acetone Is a hydration reaction in the temperature range of 30 to 55 ° C. in the coexistence of HAM.

The manganese oxide used in the present invention may be either anhydrous or hydrated.

The manganese oxide can be obtained by a known method, for example, a method of reducing a heptavalent manganese compound in a neutral to alkaline region at 20 to 100 ° C. (Zeit.anorg.allg.Chem., 309 , p. 1 to 32 and p. 121-150, (1961)); acidic method of treating potassium permanganate and manganese sulfate (Biochem.J., 50 ,
p.43, (1951)); a method of reducing a heptavalent manganate with hydrohalic acid (JP-A-63-57,535); manganese dioxide obtained by a method of electrolytically oxidizing an aqueous solution of manganese sulfate. Of these, in the method of the present invention, it is preferable to use a manganese dioxide catalyst prepared from manganese sulfate and potassium permanganate under acidic conditions with sulfuric acid in the method of the present invention.

When the catalyst is packed in a fixed bed reactor, it is usually molded into a spherical shape or a columnar shape, and its size is usually molded into a representative length of 2 to 10 mm. Also,
When the catalyst is used in a flow type catalyst suspension bed type reactor, a powder of 16 to 400 mesh is usually preferable.

Water used in the present invention is 1 mol of ACH,
It is generally 1 mol or more, preferably 2 to 20 mol, particularly preferably 4 to 10 mol.

Further, acetone has an effect of improving the activity of the manganese oxide catalyst and an effect of increasing the selectivity of HAM, and the amount thereof is usually 0.1 mol or more, and particularly preferably 0.5 to 5.0 mol per 1 mol of ACH. Used in the range.

In the present invention, the reaction temperature has a very large correlation with catalyst activity and life.

Although the catalytic activity of hydration of ACH also tends to increase as the temperature increases, the reaction temperature used in the present invention is 30 to
It is in the range of 55 ° C.

It is preferably in the range of 35 to 45 ° C, particularly preferably 35 to 40 ° C.

If the temperature is lower than 30 ° C, the activity of the catalyst becomes low, which is not practical. At temperatures above 55 ° C., the catalytic activity is high, but it decreases rapidly with time, which is not preferable.

Preferred embodiments of the present invention are as follows, for example.

The fixed bed reactor was filled with the prepared manganese dioxide catalyst, and the reaction solution prepared by mixing ACH, water and acetone in a predetermined amount was heated to a predetermined temperature by a heat exchanger, etc. Supplied at the entrance.

The inside of the fixed bed reactor is maintained at 30 to 55 ° C., and the average residence time based on ACH is usually 2 to 30 hours, preferably 4 to 10 hours.

When a flow-through type catalyst suspension bed reactor is used, the catalyst concentration in the reactor is usually 5 to 50%, preferably 10 to
A range of 30% is used.

Also, the average residence time based on ACH is usually 10 to 200 hours,
Preferably, it is used in the range of 20 to 100 hours.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

Preparation of catalyst Sulfuric acid was added to 2 l of an aqueous solution of manganese sulfate (395 g / l) to prepare an aqueous solution of manganese sulfate at pH = 1. After adding 557.2 g of potassium permanganate to this solution and oxidizing it, 1 water was added to this slurry solution while maintaining the temperature at around 50 ° C., and aged for 30 minutes.

The resulting slurry solution was suction filtered with an aspirator and dried with a drier at 110 ° C. for 12 hours to obtain 680 g of a manganese dioxide catalyst.

This manganese dioxide catalyst was molded into tablets (1/8 in x 1/8 in) using a tablet molding machine.

Example 1 In a reactor (inner diameter 28 mm, length 400 mm, made of glass) filled with 200 ml of the above-mentioned molded manganese dioxide catalyst, the reaction solution (AC
H: acetone: water molar ratio 1: 1.5: 18) was fed at a flow rate of 80 ml / hr. At this time, the flow rate of ACH is 13.7 ml / hr,
The standard average residence time was 14.6 hours.

The reactor was maintained at 38-40 ° C and operated continuously for 50 days.

Examples 2 and 3 Using the same apparatus as in Example 1, the reaction was carried out in exactly the same manner as in Example 1 except that the reaction temperature was changed to 48 to 50 ° C and 30 to 32 ° C.

Comparative Examples 1 and 2 Using the same apparatus as in Example 1, the reaction temperature was 60 ° C. and 25
The reaction was carried out in exactly the same manner as in Example 1 except that the temperature was changed to ° C.

Comparative Example 3 Using the same apparatus as in Example 1, the reaction was performed in exactly the same manner as in Example 1 except that acetone was not used.

Table 1 shows the results of the above Examples and Comparative Examples.

[Effect of the Invention] According to the present invention, in the conventional industrial continuous manufacturing method,
By solving the problem of rapid decrease in catalytic activity over time, industrially advantageous continuous production of HAM has become possible.

Claims (3)

[Claims] 1. A method for continuously producing a-hydroxyisobutyramide by continuously reacting acetone cyanohydrin and water in a liquid phase, wherein the dioxide prepared from manganese sulfate and potassium permanganate under sulfuric acid acidity. A method for producing α-hydroxyisobutyramide, which comprises subjecting a hydrated reaction to a temperature range of 30 to 55 ° C in the presence of acetone using a manganese catalyst. 2. The method according to claim 1, wherein a fixed bed reactor is used as the reactor, and the average residence time based on acetone cyanohydrin is 2 to 30 hours. 3. A flow catalyst suspension bed type reactor is used as a reactor, and the average residence time based on acetone cyanohydrin is
The method according to claim 1, which is for 10 to 200 hours.